title: The cyanide hydratase from Neurospora crassa forms a helix which has a dimeric repeat.
abstract: The fungal cyanide hydratases form a functionally specialized subset of the nitrilases which catalyze the hydrolysis of cyanide to formamide with high specificity. These hold great promise for the bioremediation of cyanide wastes. The low resolution (3.0 nm) three-dimensional reconstruction of negatively stained recombinant cyanide hydratase fibers from the saprophytic fungus Neurospora crassa by iterative helical real space reconstruction reveals that enzyme fibers display left-handed D(1) S(5.4) symmetry with a helical rise of 1.36 nm. This arrangement differs from previously characterized microbial nitrilases which demonstrate a structure built along similar principles but with a reduced helical twist. The cyanide hydratase assembly is stabilized by two dyadic interactions between dimers across the one-start helical groove. Docking of a homology-derived atomic model into the experimentally determined negative stain envelope suggests the location of charged residues which may form salt bridges and stabilize the helix.
authors.affiliation: Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch, 7700 South Africa.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Dent
authors.forename: Brandon W
authors.initials: BW
authors.lastname: Weber
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Benedik
authors.forename: B Trevor
authors.initials: BT
authors.lastname: Sewell
mesh_terms: D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015870:Gene Expression; D006836:Hydro-Lyases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000737:chemistry / Q000201:enzymology*; D016415:Sequence Alignment
chemical_list: D005656:Fungal Proteins; D006836:Hydro-Lyases; C076848:cyanide hydratase